The present invention relates to a liquid crystal color display device employing a liquid crystal element or unit as a light switching element.
Heretofore, color display devices have typically employed CRTs (cathode-ray tubes) and have widely been used in television display units, OA (office automation) components, and other display units. The CRT is a type of vacuum tube having a large conical shape. The display unit composed of the CRT must therefore be powered by a high-voltage power supply, requires a complex driver circuit, and is large in overall size, with the result that the display unit could not be thinned down beyond a certain limit.
Recent years have seen the development of panel-shaped liquid crystal display devices, which have resulted in pocketable liquid crystal color television receivers. As described in a Japanese periodical "Nikkei Electronics", 1984, 9-10, pages 211 to 240, such a pocketable liquid crystal color television receiver comprises a liquid crystal panel composed of a glass plate having red, green, and blue color filters assigned to each pixel, another transparent plate with an array of thin-film transistors disposed thereon, a TN (twisted nematic) liquid crystal material sealed between the plates, and a pair of polarizers sandwiching the plates, and an illuminating light source positioned behind the liquid crystal panel. The thin-film transistors are fabricated in association with the red, green, and blue color filters of the respective pixels for switching light.
Although the liquid crystal color display device described above can be constructed in a low profile, it is still disadvantageous in that color generation and reproduceability are insufficient due to the use of a white-light lamp as the illuminating light source and of the optical filters, displayed images have a low contrast and hence cannot be seen well, and the illuminating light source has a large power requirement.